1. Field of the Invention
The present invention relates to a printing apparatus and a printing method, and in particular, to a printing apparatus and a printing method that suppress generation of density unevenness caused by an oblique motion of a print medium.
2. Description of the Related Art
There is known a method of printing an image on a print medium by scanning a predetermined printing area (band) by one time or plural times (one pass or multi-pass) while conveying the print medium in a printing apparatus. According to this printing method, there are some cases where a streak-shaped density unevenness (hereinafter, called “a connecting streak”) is generated in a connecting section between the predetermined printing areas due to an error of a conveyance amount of the print medium or the like.
For suppressing generation of this connecting streak, Japanese Patent Laid-Open No. 2007-190861 discloses an image forming apparatus in which a density changing amount is found from a conveyance error of a print medium and a pitch between print elements and γ processing using a correction γ value is executed to image data corresponding to print elements positioned in both ends of the print medium in a conveying direction, based upon this density changing amount. In addition, Japanese Patent Laid-Open No. 2012-126016 discloses an inkjet printing apparatus in which a reduction rate in the amount of ink which is ejected on a predetermined area in the vicinity of the boundary between adjacent printing areas is determined based upon a conveyance shift amount of the print medium and an ink amount to reduce the amount of ink.
The configuration of each of the apparatuses disclosed in Japanese Patent Laid-Open No. 2007-190861 and Japanese Patent Laid-Open No. 2012-126016 takes the event that there occurs the error in the conveyance amount of the print medium into account, but does not take the event that there occurs an oblique motion of the print medium at the time of conveying the print medium into account. That is, the conveyance error of the same amount is assumed to occur in the conveying direction, and therefore the correction is made by the same value or the same reduction rate in a main scan direction. In consequence, the connecting streak cannot be appropriately suppressed in a case where there occurs the oblique motion by which the conveyance amount in the conveying direction differs for each area of the print medium